Crossbows embodying the general and well-known constructional principles of a bow mounted on a supporting stock have recently become more widely utilized. Crossbows are now more frequently utilized for purposes of hunting game animals in addition to being used for competition matches by their enthusiasts.
As indicated, crossbow, in its general construction, includes a generally conventional bow which is mounted upon and carried on a supporting structure generally characterized as a gunstock and its associated forearm. The bow includes a strong resilient limb or set of limbs secured to a forward portion of the stock and forearm and has a string adapted to engage with a projectile such as a bolt or an arrow. Also included in the structure of crossbow is a trigger mechanism which has the appearance of a trigger for conventional firearms and is operable for a same general purpose. However, in a crossbow, the trigger mechanism, rather than operating upon a firing pin, includes a mechanism designed for engaging with and retaining the bowstring in a cocked position where it is able to then impart the necessary force for propulsion of the projectile. The stock and forearm often provide means of initial guidance for the projectile to enhance the accuracy of the crossbow. The trigger mechanism, in general, includes a device which forms a stop element around which the bowstring is strung when cocked and this element then is permitted to move to a position where the string is released upon actuation of the trigger and enable functional operation of the crossbow.
Safety in the operation of a crossbow has become a matter of great importance due to the increased number of crossbow enthusiasts and their increasing usage. A crossbow, in its basic construction, has an inherent safety problem in that trigger mechanisms designed to operate in the desired manner can be very easily caused to inadvertently function and release the bowstring. Consequently, efforts have been made to construct trigger mechanisms to incorporate a sefety device or mechanism to better assure that the mechanism can be maintained in an operating state that will prevent inadvertent or accidental functioning of the trigger to release the string holding element of the mechanism. The safety devices, in general, comprise a structure incorporating a locking lever or element which cooperates with the trigger so as to maintain the trigger in a position that will retain the string holding element in its holding position until such time as the safety element is released or is moved to an arming position with respect to the trigger. It is also a desired constructional feature of trigger mechanisms incorporating safety mechanism to have the mechanism operate in an essentially automatic manner during the operation of cocking of the string so that upon positioning of the string holding element in its string holding position, the trigger would not only be in a position to retain the string holding element in that position, but the safety device will also be operated to place it in a position where it will function to prevent operation of the trigger.
Exemplary of prior structures designed to accomplish these general objectives is the mechanism disclosed in U.S. Pat. No. 3,490,429 issued Jan. 20, 1972 to D. S. Benedict. That mechanism includes a string holding element in the form of a device mounted for rotational movement between a string holding and a string releasing position and a trigger which cooperates with the string holding element to lock it in a string holding position. A safety device in the form of a rotatable cam shaft is positioned to cooperate with the trigger. This cam shaft has a surface configuration such that, depending upon the particular position to which it is rotated, it will either engage the trigger to prevent its movement out of locking engagement with the string holding element or will permit slight rotational movement of the trigger to permit functioning with consequent release of the bowstring. The safety device is provided with a spring which continually urges the safety element to a safetying position by causing rotation of the cam shaft to a trigger locking position. A disadvantage of this structure is that, in order to permit operation of the trigger mechanism, the operator must also maintain the safety element in the nonsafetying position while concurrently and simultaneously operating the trigger member. This structure, however, does have a structure capable of achieving the desired objective of placing the safety in a safetying position automatically upon cocking of the bowstring.
Another example of a structure for an automatically functioning safety in a crossbow trigger mechanism is that shown in U.S. Pat. No. 4,030,473 granted June 21, 1977 to John W. Puryear. This structure also includes the three basic elements of a string holding element, trigger lever and a safety locking device. The elements are arranged in such a manner that, during the cocking operation as the string is drawn into the string holding element, the string will also concurrently cooperate in engagement with the locking element so as to effect displacement of the locking element into a locked position in association with the trigger. The disadvantage of the particular structure as shown in U.S. Pat. No. 4,030,473 is that the cocking operation, so as to effect the setting of the safety, requires a greater displacement of the string than is actually required to place the string in a cocked position.
A third example of a structure intended to achieve the objective of automatic setting of a safety device on a trigger mechanism for a crossbow is illustrated in U.S. Pat. No. 4,192,281 granted Mar. 11, 1980 to Fred V. King. The structure shown in this patent for a trigger mechanism is similar to the basic trigger mechanism for crossbows and in addition, operates in a similar manner to that of U.S. Pat. No. 4,030,473. In U.S. Pat. No. 4,192,281, the structure includes a string holding element which is rotatable about a pivot axis and is held in a storing holding position by a trigger lever. A safety lever is provided which operates on the trigger lever to maintain it in a locked position until selectively displaced to an unlocking position. The function of this mechanism is similar to that of Puryear in that cocking of the bow by drawing the string to a cocked position requires that the string must be moved a greater distance than when ultimately placed in its held position to effect operation of the safety lever.
U.S. Pat. No. 3,924,599 issued Dec. 9, 1975 to William D. Hammond illustrates a trigger mechanism for a compressed-air gun which is non-analogous to the crossbow art, but is nevertheless deemed relevant with respect to illustrating a spring mechanism interconnected with a safety or locking lever and a trigger lever. The trigger lever shown in that patent disclosure comprises two elements that are separately mounted for pivotal movement, but are mechanically interconnected for cooperative movement to either hold or release a spring device that generates the projectile propelling energy. The safety lever is always biased to a safety position by the spring interconnecting with the trigger lever and which spring concurrently biases the trigger lever to the hold position. A cocking operation temporarily displaces the safety lever to its unsafe position in order to enable cocking of the gun. An examination of the pivot and fulcrum points of the safety lever and the biasing spring shows that this mechanism is also of the type requiring that the safety lever be simultaneously held in the unsafe position while pulling the trigger.